Tubular hydro-extractor for purifying suspensions of fibrous material



May 31, 1955 H. BANNING 2,709,397

. TUBULAR HYDRO-EXTRACTOR FOR PURIFYING SUSPENSIONS OF FIBROUS MATERIAL Filed July 6, 1951 Inventor: Helmuth Banning nited TUBULAR HYDRO-EXTRACTOR FOR PURIFYING SUSPENSIONS F FIBROUS MATERIAL Helmuth Banning, Duren (Rhineland), Germany, assiguor to O. Diirries A. G. vorm. Maschinenfabrik Banning 8.: Seybold, Duren (Rhineland), Germany Application July 6, 1951, Serial No. 235,536 Claims priority, application Germany July 19, 1950 3 Claims. (Cl. 92-28) said hollow cylinder; the impurities being of greater I density, are subject to a stronger centrifugal force, and are thus carried to the periphery, and flow into the lower, and usually funnel-shaped and thus narrower, end of the said hollow cylinder towards the central aperture of the said funnel. A proportion of good fibrous material is carried into the sump below said aperture, so that a very considerable loss of usable fibres occurs; furthermore, the sump has to be emptied more often, thus causing heavier demands on maintenance.

It has been proposed to introduce additional water into the suspension in the lower part of the tubular extractor i. e. in the aforesaid funnel where the suspension is not rotating, in order that the impurities may settle quicker in the thus diluted and still suspension.

This addition of clean water can however exert a noticeable effect only at the price of a considerable diminution of density in the lower part of the tubular extractor, thus often reducing the density of the entire body of the suspension to be purified to an inadmissible degree.

By means of the method and of the device the description of which follows, the separation from the impurities of the fibres which are being carried away and their reincorporation in the purified fibrous material can be accomplished without producing an appreciable alteration of the density of the suspension.

According to the present invention when using a tubular extractor for the purifying of suspensions of fibrous materials, a thin stream of clean water is introduced from the inner surface of the said tubular extractor concentrically into the unpurified suspension of fibrous material which is moving helically downwards. Owing to their higher centrifugal force, the impurities are driven from the periphery of the helical flow of liquid into the clean water stream and displace an equivalent volume of clean water; the latter, whilst moving from the periphery towards the axis of the helical flow, flushes out the fibres which were carried along by the impurities, and carries them along back to the purified fibrous material.

The method according to the present invention makes it possible, when purifying suspensions of fibrous materials by means of tubular extractors, to eliminate practically any loss of good fibres and furthermore to increase considerably operating time between successive clearances of the sump, thus simplifying the servicing of tubular extractors.

A tubular hydro-extractor adapted for carrying out the method according to the present invention is preferably provided with a circular slit serving as water inlet at, or closely above, at least one turning point of the vortex. If the said slit is situated at or closely above rates Patent 0 ice one turning point of the vortex, clean water flows in at a point at which the impurities have been moved to the extreme periphery of the helical flow so that the highest possible effect is'achieved. If the extractor has several turning points of the vortex, water inlets can be provided accordingly at various points.

The rotary movement of the suspension can be influenced by introducing the clean water tangentially into the said slit. Instead of by this tangential inflow, rotary movement can be imparted to the clean water by means of guides.

In order that the invention may be more fully understood there follows a description with reference to the accompanying drawing of one embodiment; this embodiment is given by way of example only.

In the drawing, Fig. 1 is a diagrammatic vertical sec tion of a tubular hydro-extractor, and

Fig. 2 is a horizontal section through the tangential inlet.

Referring to the drawing, the tubular hydro-extractor comprises an extractor tube 1 having a tube head 11 at its upper end. The head 11 is provided with a tangential inlet 12 for the unpurified suspension and a coaxial outlet 13 for the purified suspension, which outlet 13 extends below the opening of the inlet 12.

A circular slit 2 is provided at the lower end of the extractor tube 1; this slit is surrounded by an annular channel 3. A water inlet pipe 4 opens into the said annular channel 3 and is preferably disposed tangentially to the latter. On the lower end of the extractor tube 1 a funnel S is mounted by means of Which the impurities pass through a check valve 6 into the sump 7.

In operation of the hydro-extractor, the suspension moves downward in an outer vortex in the extractor tube 1, and before reaching the upper rim of the funnel 5, passes the circular slit 2, at which stage water forced from the inlet pipe 4 into the annular channel 3 enters the extractor tube 1 under a pressure which is at least equal to the pressure exerted upon the wall of the extractor tube 1. After passing the circular slit 2 the impurities are impelled by centrifugal force into the clean water, the latter being lighter and thus tending to move inward. Whilst thus moving it traverses the suspension vortex and carries ofi" fibres which offer stronger resistance. Whilst the purified suspension along with the added water moves upward in an inward vortex, the impurities from which the fibres have been separated and removed, accumulate at the top of the funnel 5 from where they proceed through the check valve 6 into the sump 7. The exact position of the inlet slits for the clean water is not of decisive importance, but these slits should expediently be placed at points at which practically all the impurities are pressed against the outer surface.

I claim:

1. In a tubular hydro-extractor for purifying suspensions having a vertical tube long relative to its diameter, a tangential inlet at the upper end for suspension and a central outlet for purified suspension, an outlet for impurities at the lower end of said tube, the improvement which comprises at least one substantially circular slit in said tube above the outlet for impurities and substantially below said inlet, and means for introducing a stream of water into said tube through said slit.

2. In a tubular hydro-extractor for purifying suspensions having a vertical tube long relative to its diameter, a tangential inlet at the upper end for suspension and a central outlet for purified suspension, an outlet for impurities at the lower end of said tube, the improvement which comprises at least one substantially circular slit in said tube above the outlet for impurities and substantially below said inlet, and means for introducing a stream of Water into said tube through said slit, said means including a channel surrounding said slit and means for introducing said water tangentially into said tube through said slit 3. In a tubular hydro-extractor for purifying suspensions having a vertical tube long relative to its diameter, a tangential inlet at the upper end for suspension and a central outlet for purified suspension, an ouflet for impurities at the lower end of said tube, the improvement which comprises at least one substantially circular slit in said tube above the outlet for impurities and substantially below said inlet, and means for in- -i trodu'cing a stream of water into said tube through said slit, said means introducing said water tangentially into said tube through said slit.

References Cited in the file of this patent UNITED STATES PATENTS 762,557 Allen s June 21, 1904 2,102,525 Freeman Dec. 14, 1937 2,207,218 Forma'n July 9, 1940 2,346,005 Bryson Apr. 4, 1944 2,512,253 Lipscomb June 20, 1950 2,610,737 Eder Sept. 16, 1952 

1. IN A TUBULAR HYDRO-EXTRACTOR FOR PURIFYING SUSPENSIONS HAVING A VERTICAL TUBE LONG RELATIVE TO ITS DIAMETER, A TANGENTIAL INLET AT THE UPPER END FOR SUSPSENSION AND A CENTRAL OUTLET FOR PURIFIED SUSPENSION, AN OUTLET FOR IMPURITIES AT THE LOWER END OF SAID TUBE, THE IMPROVEMENT WHICH COMPRISES AT LEAST ONE SUBSTANTIALLY CIRCULAR SLIT IN SAID TUBE ABOVE THE OUTLET FOR IMPURITIES AND SUBSTANTIALLY BELOW SAID INLET, AND MEANS FOR INTRODUCING A STREAM OF WATER INTO SAID TUBE THROUGH SALT SLIT. 